Sterling's water treatment plant will be ready by late summer, says contractor

Process hits snags, mystery "black material"

Those tapped in to Sterling's pipes will have to wait a bit longer for their newly filtered water, a representative from the contractor in charge of the new Water Treatment Plan told the Sterling City Council Tuesday evening.

Some unexpected hang-ups have pushed back the time before residents receive the full benefits of the new water treatment plant until late summer.

The plant has been filtering the city's water since November, but the full 80/20 reverse osmosis (RO)-filtered water to regular filtered water mix will eke its way into Sterling's system over the next several months.

Plans to build the plant started around September 2008, when the Colorado Department of Public Health and Environment issued an enforcement order to get the city's water up to compliance with Environmental Protection Agency standards within a given time frame. The main contaminant, among others, was the water 's naturally-occurring uranium levels, which could increase a person's cancer risk over longer exposures.

The water treatment plant will significantly lower uranium and pollutant levels, and significantly drop the hardness of the water.

Most of the issues crews ran into concerned well and distribution issues, but one stood out: A thick, black, non-cohesive material in the well water was clogging up filters faster than expected.

“We don't know entirely what it is,” said Rob Demis, of Hatch Mott MacDonald, the company overseeing construction of the plant. He brought a bottle of it to show the council, showing it as fine black sediment layered at the bottom of clear ground water.

Advertisement

After a couple of shakes, the water turned black and opaque.

The material – 20 percent organic material and 30 percent manganese, with traces of other elements, such as iron and silicon – is also odorless, though Demis guessed it would have tasted “metallic” and “bitter.” The manganese gives the material its color.

The raw water filter running now, which catches sediment down to the one-micron level, has caught the material at the five-micron level. Crews would change the filters every couple of days in November, but it's since become less prevalent, which Demis credited to the city's aggressive pipe flushing program.

“We don't know the origin. It may be coming out of the pipes. It may be coming out of the formations,” he said. “The good news now is we're filtering it.”

The plant also encountered issues with its distribution system, which wasn't getting water out of the plant quick enough to the city's distribution tanks to fill them. Demis said the plant quickly fills Sterling's north and south tanks but doesn't reach its west tank.

Part of the problem might be buildup in the pipes over the years slowing water flow (like plaque clogging an artery, Demis said), but many of the pipes are also 100 years old.

“When you've got pipes that are 100 years old, the records on the size of the pipe, what's in the ground, may not be all that good,” he said.

The problem is “relatively easy” to fix.

But crews are also working to get more water from the raw water wells.

The plant had planned on having the ability to pump more than 7,900 gallons of water per minute, but right now it can only pump about 5,500. That means that of the treatment plant's three pump levels – the third allowing the maximum amount of water to pump during peak use – they can only pump enough water to fulfill the first two.

Demis said the crews are still trying to rehabilitate the wells, which have been degraded and worn out over time.

Water treatment crews have also been finishing construction on two deep water injection wells, which will deposit treated waste water more than a mile underground. One of the wells was dug at about 7,200 feet underground, as recommended by EPA estimates, while the second was dug to about 6,100 feet.

Demis said the area's geology hasn't been fully explored, so the crew will need to test the area over time.

While the project still has about $2.9 million left in its budget, between $1.6 million and $2 million of that will go toward the well's construction, testing and completion. The 7,200-foot well should be completed by early summer, while the second should be completed by late summer.

When asked about previous estimates that the 80/20 mix could start flowing by the end of March, Demis said the physical construction of the water treatment plant might be done by then, but the water would take longer to reach customers.

Other water treatment plant officials had previously said employees would start checking the systems in January.

City Manager Joe Kiolbasa said the city could receive the correct mix now, but only for about six hours per day.

The city will slowly add more RO water to the mix as the treatment plant comes closer to completion, but Kiolbasa said the changes might not be announced.

Plant crews might increase or decrease the amount of RO water they can use, depending on additions or corrections they need to make to the system. In the mean time, Demis said the water might have a milky or red color, odor and taste issues and re-suspended sediment at points as the water's new chemistry dissolves deposits on the city's pipes.

The changes might also cause pipes to break as deposits loosen, but water conditions will eventually return to normal.

Article Comments

We reserve the right to remove any comment that violates our ground rules, is spammy, NSFW, defamatory, rude, reckless to the community, etc.

We expect everyone to be respectful of other commenters. It's fine to have differences of opinion, but there's no need to act like a jerk.

Use your own words (don't copy and paste from elsewhere), be honest and don't pretend to be someone (or something) you're not.

Our commenting section is self-policing, so if you see a comment that violates our ground rules, flag it (mouse over to the far right of the commenter's name until you see the flag symbol and click that), then we'll review it.